U.S. patent number 6,199,307 [Application Number 09/321,546] was granted by the patent office on 2001-03-13 for battery-powered working machine.
This patent grant is currently assigned to Kabushiki Kaisha Kobe Seiko Sho. Invention is credited to Masayuki Kagoshima, Hideki Kinugawa.
United States Patent |
6,199,307 |
Kagoshima , et al. |
March 13, 2001 |
Battery-powered working machine
Abstract
It is intended to keep low the moment of inertia of a boom, etc.
and maintain the whole of a working machine in good weight balance.
At the same time, a highly efficient recovery of energy is to be
attained to increase a continuous working time of a battery. A
battery-powered working machine using a battery as a power source
is provided. Rotation of a rotatable superstructure 12 and rising
and falling motions of a boom 28 are performed directly by electric
motors 22 and 34. The recovery of energy is attained by utilizing
the electric motors 22 and 34. An arm 30 and a bucket 32 both
located remote from a centroid position of the machine are actuated
by an arm cylinder 38 and a bucket cylinder 40, which are hydraulic
actuators less heavy than electric motors. Further, a hydraulic
pump 18 for supplying those hydraulic actuators with a hydraulic
oil is actuated by a hydraulic pump actuating electric motor 20
which utilizes the battery 14 as a power source.
Inventors: |
Kagoshima; Masayuki (Kobe,
JP), Kinugawa; Hideki (Hiroshima, JP) |
Assignee: |
Kabushiki Kaisha Kobe Seiko Sho
(Kobe, JP)
|
Family
ID: |
15519135 |
Appl.
No.: |
09/321,546 |
Filed: |
May 28, 1999 |
Foreign Application Priority Data
|
|
|
|
|
Jun 1, 1998 [JP] |
|
|
10-151465 |
|
Current U.S.
Class: |
37/443;
60/420 |
Current CPC
Class: |
E02F
3/325 (20130101); E02F 9/2296 (20130101); E02F
9/207 (20130101); E02F 9/2095 (20130101) |
Current International
Class: |
E02F
9/20 (20060101); E02F 9/22 (20060101); E02F
3/34 (20060101); E02F 3/28 (20060101); F16D
031/02 (); E02F 003/32 () |
Field of
Search: |
;37/348,443,466,905
;414/685,686,687,917,918,718,728 ;180/9.1,234,167 ;701/50
;60/400,420,431 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pezzuto; Robert E.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier,
& Neustadt, P.C.
Claims
What is claimed is:
1. A battery-powered working machine including a boom attached to a
body of the working machine so as to be capable of rising and
falling, a working portion attached to said boom, and a battery as
a drive source, said battery-powered working machine
comprising:
a boom actuating electric motor which is supplied with electric
power from said battery and which actuates said boom directly;
a hydraulic pump;
a hydraulic pump actuating electric motor which is supplied with
electric power from said battery and which actuates said hydraulic
pump; and
a hydraulic actuator which is supplied with hydraulic oil
discharged from said hydraulic pump and which actuates said working
portion attached to said boom.
2. A battery-powered working machine including a rotatable
superstructure carried rotatably on a lower carriage, a boom
attached to said rotatable superstructure so as to be capable of
rising and falling, a working portion attached to said boom, and a
battery as a drive source, said battery-powered working machine
comprising:
a rotating electric motor which is supplied with electric power
from said battery and which directly causes said rotatable
superstructure to rotate;
a hydraulic pump;
a hydraulic pump actuating electric motor which is supplied with
electric power from said battery and which actuates said hydraulic
pump; and
a hydraulic actuator which is supplied with hydraulic oil
discharged from said hydraulic pump and which actuates said working
portion attached to said boom.
3. A battery-powered working machine including a rotatable
superstructure carried on a lower carriage rotatably, a boom
attached to said rotatable superstructure so as to be capable of
rising and falling, a working portion attached to said boom, and a
battery as a drive source, said battery-powered working machine
further including:
a boom actuating electric motor which is supplied with electric
power from said battery and which actuates said boom directly;
a rotating electric motor which is supplied with electric power
from said battery and which directly causes said rotatable
superstructure to rotate;
a hydraulic pump;
a hydraulic pump actuating electric motor which is supplied with
electric power from said battery and which actuates said hydraulic
pump; and
a hydraulic actuator which is supplied with hydraulic oil
discharged from said hydraulic pump and which actuates said working
portion attached to said boom.
4. The battery-powered working machine according to any of claims 1
to 3, wherein said working portion is an arm connected rotatably to
a front end portion of said boom and which further includes an arm
actuating hydraulic actuator, said arm actuating hydraulic actuator
being supplied with the hydraulic oil discharged from said
hydraulic pump and causing said arm to rotate.
5. The battery-powered working machine according to any of claims 1
to 3, wherein said working portion comprises an arm connected
rotatably to a front end portion of said boom and a bucket
connected rotatably to a front end portion of said arm and which
further includes a bucket actuating hydraulic actuator, said bucket
actuating hydraulic actuator being supplied with the hydraulic oil
discharged from said hydraulic pump and causing said bucket to
rotate.
6. The battery-powered working machine according to any of claims 1
to 3, wherein said working portion comprises an arm connected
rotatably to a front end portion of said boom and a bucket
connected rotatably to a front end portion of said arm and which
further includes an arm actuating hydraulic actuator, said arm
actuating hydraulic actuator being supplied with the hydraulic oil
discharged from said hydraulic pump and causing said arm to rotate,
and a bucket actuating hydraulic actuator, said bucket actuating
hydraulic actuator being supplied with the hydraulic oil discharged
from said hydraulic pump and causing said bucket to rotate.
7. The battery-powered working machine according to any of claims 1
to 3, further comprising tires for the travel of said working
machine itself and a traveling electric motor which is supplied
with electric power from said battery and which directly causes
said tires to rotate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a working machine such as an
excavator which is operated using a battery as a drive source.
2. Description of the Prior Art
Usually, in a conventional working machine such as a hydraulic
excavator, a hydraulic pump is actuated by utilizing the power of
an engine mounted for traveling and a hydraulic oil discharged from
the hydraulic pump is fed to various hydraulic actuators such as a
rotating motor, a boom cylinder and an arm cylinder to actuate
various portions. However, in such a machine utilizing the engine
power, there is a fear that noises and exhaust gases generated from
the engine may exert a bad influence on the working site
environment. For this reason it is the present situation that
strict restrictions are placed on operations in cities and towns
and in tunnels, further, on night operations.
In an effort to eliminate such bad influence there has recently
been proposed a working machine wherein an electric motor is
rotated by utilizing the electric power of a battery mounted on the
working machine and a hydraulic pump is actuated by the electric
motor (see, for example, Japanese Patent Laid Open No.
9-144061).
The battery mounted on the above working machine is lower in energy
density (energy capable of being stored per unit mass) than fossil
fuels such as gasoline and gas oil which are engine fuels. Thus,
battery-powered working machine is disadvantageous in that the
continuous working time is short as compared with working machines
which utilize the engine power. As an example of means for
increasing the continuous working time there is mentioned a means
wherein energy is recovered when a negative work such as boom
lowering or rotation braking work is performed and it is
regenerated in the battery (that is, the attainment of a high
efficiency is intended by energy regeneration). However, a large
number of valves, including electromagnetic proportion valves, are
mounted on a hydraulic excavator or the like and there occurs a
large pressure loss or relief loss in those valves, so that it is
very difficult to effect an efficient recovery of energy to the
battery through the medium of such a hydraulic circuit.
If the operation of the boom and the rotation are conducted
directly with use of an electric motor which is driven by a
battery, without using such a hydraulic circuit, it will be
possible to effect an efficient recovery of energy. However, in
comparison with the hydraulic actuator, such an electric motor is
smaller in the force and torque which it can generate per unit
weight; besides, a reduction mechanism is required. Thus, the use
of such a battery-powered electric motor is disadvantageous in that
moving portions becomes more complicated in structure than in the
use of a hydraulic actuator. The weight of moving portions also
increases. Therefore, if the electric motor in question is provided
at the front end of a boom, not only the moment of inertia of the
boom and that of the entire swing structure will become larger, but
also the weight balance of the entire working machine will become
unstable.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the
above-mentioned circumstances and it is an object of the invention
to provide a battery-powered working machine capable of keeping low
the moment of inertia of a boom, etc. and capable of effecting a
highly efficient recovery of energy to increase the continuous
working time while maintaining the entire working machine in good
weight balance.
According to the present invention, for achieving the
above-mentioned object, there is provided in one aspect thereof a
battery-powered working machine including a boom attached to a body
of the working machine so as to be capable of rising and falling, a
working portion attached to the boom, and a battery as a drive
source, the working machine further including a boom actuating
electric motor which is supplied with electric power from the
battery and which actuates the boom directly, a hydraulic pump
actuating electric motor which is supplied with electric power from
the battery and which actuates a hydraulic pump, the hydraulic pump
which is actuated by the hydraulic pump actuating electric motor
and which discharges a hydraulic oil, and a hydraulic actuator
which is supplied with the hydraulic oil discharged from the
hydraulic pump and which actuates the working portion attached to
the boom.
According to the present invention there is provided in another
aspect thereof a battery-powered working machine including a
rotatable superstructure carried rotatably on a lower carriage, a
boom attached to the rotatable superstructure so as to be capable
of rising and falling, a working portion attached to the boom, and
a battery as a drive source, the working machine further including
a rotating electric motor which is supplied with electric power
from the battery and which directly causes the rotatable
superstructure to rotate, a hydraulic pump actuating electric motor
which is supplied with electric power from the battery and which
actuates a hydraulic pump, the hydraulic pump which is actuated by
the hydraulic pump actuating electric motor and which discharges a
hydraulic oil, and a hydraulic actuator which is supplied with the
hydraulic oil discharged from the hydraulic pump and which actuates
the working portion attached to the boom.
According to the present invention there is provided in a further
aspect thereof a battery-powered working machine including a
rotatable superstructure carried on a lower carriage rotatably, a
boom attached to the rotatable superstructure so as to be capable
of rising and falling, a working portion attached to the boom, and
a battery as a drive source, the working machine further including
a boom actuating electric motor which is supplied with electric
power from the battery and which actuates the boom directly, a
rotating electric motor which is supplied with electric power from
the battery and which directly causes the rotatable superstructure
to rotate, a hydraulic pump actuating electric motor which is
supplied with electric power from the battery and which actuates a
hydraulic pump, the hydraulic pump which is actuated by the
hydraulic pump actuating electric motor and which discharges a
hydraulic oil, and a hydraulic actuator which is supplied with the
hydraulic oil discharged from the hydraulic pump and which actuates
the working portion attached to the boom.
In these working machines, since the boom and the rotatable
superstructure are actuated directly by electric motors (that is,
they are actuated through mechanical means such as reduction gears
without through any hydraulic means), the mechanisms associated
with the said actuation can be simplified. Besides, when a negative
work is performed such as moving down the boom at a predetermined
speed against its own weight or braking the rotatable
superstructure during rotation, the boom actuating electric motor
or the rotating electric motor are allowed to function as a
generator, thereby converting the said negative work into an
electric energy, which can be recovered in the battery. On the
other hand, a hydraulic actuator, which is less heavy than the
electric motors, is used for actuating the working portion located
farther from the centroid position of the working machine than the
boom and the rotatable superstructure. Further, a hydraulic pump is
actuated by a hydraulic pump actuating electric motor which uses
the battery as a drive source, to supply the hydraulic actuator
with hydraulic oil. In this way it is possible to avoid a great
increase in inertia moment of the rotatable superstructure and the
boom and avoid deterioration of the weight balance of the entire
working machine.
The working portion attached to the boom comprises, for example, an
arm connected rotatably to the front end portion of the boom and a
bucket connected rotatably to the front end portion of the arm. In
this connection, it is preferable for the working machine to be
provided with an arm actuating hydraulic actuator which is supplied
with the hydraulic oil from the hydraulic pump and which causes the
arm to rotate and a bucket actuating hydraulic actuator which is
supplied with the hydraulic oil from the hydraulic pump and which
causes the bucket to rotate.
In the case where tires, which are smaller in frictional resistance
with the ground surface than crawlers and which is hence smaller in
energy loss caused by the said friction, are used as means for
causing the working machine itself to travel, it is preferable for
the working machine to be provided with a traveling electric motor
which is supplied with an electric power from the battery and which
directly causes the tires to rotate. By so doing, it becomes
possible to effect the recovery of energy in a still higher
efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a is a front view of a hydraulic excavator according to the
first embodiment of the present invention and FIG. 1b is a plan
view thereof;
FIG. 2 is a configuration diagram showing drive units mounted on
the hydraulic excavator of FIGS. 1a and 1b;
FIG. 3a is a front view of a hydraulic excavator according to the
second embodiment of the present invention and FIG. 3b is a plan
view thereof; and
FIG. 4 is a configuration diagram showing drive units mounted on
the hydraulic excavator of FIGS. 3a and 3b.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The first embodiment of the present invention will be described
hereinunder with reference to FIGS. 1 and 2.
The hydraulic excavator shown in FIG. 1 is provided with a lower
carriage 10 having tires 11 for travel. A rotatable superstructure
12 is mounted on the lower carriage 10 so as to be rotatable about
a vertical axis. In the rotatable superstructure 12 is provided a
cab 13, and further mounted are a battery 14, a hydraulic tank 16,
a hydraulic pump 18, a hydraulic pump actuating electric motor 20,
and a rotating electric motor 22. The rotating electric motor 22 is
connected to a rotating drive mechanism 24 through a reduction
mechanism 23. The whole of the rotatable superstructure 12 is
rotated by operation of the electric motor 22. Further, a left-hand
traveling electric motor 26L and a right-hand traveling electric
motor 26R are connected to the front left and right tires
respectively through a left-hand reduction mechanism 25L and a
right-hand reduction mechanism 25R. The whole of the hydraulic
excavator is caused to travel by operation of the electric motors
26L and 26R.
A base end portion of a boom 28 is connected to a front end portion
of the rotatable superstructure 12 so as to be rotatable (capable
of rising and falling) about a shaft disposed in the transverse
direction of the hydraulic excavator. To a front end portion of the
boom 28 is connected a base end portion of a arm 30 so as to be
rotatable about a shaft disposed in the transverse direction of the
excavator, and to a front end portion of the arm 30 is connected a
base end portion of a bucket 32 so as to be rotatable about a shaft
disposed in the transverse direction of the excavator. An
intermediate part of the boom 28 and the base end portion of the
arm 30 are connected with each other through an arm cylinder (an
actuator for the arm) 38. The arm 30 is rotated by expansion and
retraction of the arm cylinder 38. The base end portion of the arm
30 and that of the bucket 32 are connected with each other through
a bucket cylinder (an actuator for the bucket) 40. The bucket 40 is
rotated by expansion and retraction of the bucket cylinder 40.
Drive units mounted on the hydraulic excavator are shown in FIG. 2.
An output shaft of the hydraulic pump actuating electric motor 20
is connected to a rotating shaft of the hydraulic pump 18. The
hydraulic pump 18 is actuated by operation of the motor 20 and
discharges hydraulic oil from the interior of the hydraulic tank 16
to a hydraulic circuit 50. In the hydraulic circuit 50 are provided
various control valves such as electromagnetic proportion valves,
and the hydraulic oil is fed through the hydraulic circuit to the
arm cylinder 38 and the bucket cylinder 40 to expand or retract the
arm cylinder and the bucket cylinder.
On the other hand, in the cab 13 are provided a boom operating
lever 41, an arm operating lever 42, a bucket operating lever 43, a
rotation operating lever 44, a right travel operating lever 46R,
and a left travel operating lever 46L. Command signals, which are
outputted in accordance with operations of these operating levers,
are inputted to a control circuit 48. The hydraulic pump actuating
electric motor 20, boom actuating electric motor 34, rotating
electric motor 22 and traveling electric motors 26L, 26R are
connected to the control circuit 48, to which is also connected the
battery 14 as a drive source for those motors. The control circuit
48 is configured to perform the following controlling operations in
accordance with the command signals provided from the operating
levers.
1 Outputs a control signal to the boom actuating electric motor 34
in accordance with operation of the boom operating lever 41 and
causes the boom 28 to rise or fall in a direction matching the
operating direction and at a speed matching the operation
quantity.
2 Outputs a control signal to the rotating electric motor 22 in
accordance with operation of the rotation operating lever 44 and
causes the rotatable superstructure 12 to rotate in a direction
matching the operating direction and at a speed matching the
operation quantity.
3 Outputs a control signal to the left-hand traveling electric
motor 26L in accordance with operation of the left travel operating
lever 46L and causes the left tires 11 to rotate in a direction
matching the operating direction and at a speed matching the
operation quantity. Likewise, the control circuit 48 outputs a
control signal to the right-hand traveling electric motor 26R in
accordance with operation of the right travel operating lever 46R
and causes the right tires 11 to rotate in a direction matching the
operating direction and at a speed matching the operation
quantity.
4 Outputs control signals to the hydraulic pump actuating electric
motor 20 and also to various solenoid valves in the hydraulic
circuit 50 in accordance with operation of the arm operating lever
42 and causes the hydraulic oil to be fed to the arm cylinder 38 so
that the arm 30 rotates in a direction matching the operating
direction and at a speed matching the operation quantity. Likewise,
outputs control signals to the hydraulic pump actuating electric
motor 20 and also to various solenoid valves in the hydraulic
circuit 50 in accordance with operation of the bucket operating
lever 43 and causes the hydraulic oil to be fed to the bucket
cylinder 40 so that the bucket 32 rotates in a direction matching
the operating direction and at a speed matching the operation
quantity.
In this hydraulic excavator, the boom 28 is actuated directly by
the boom actuating electric motor 34 (that is, actuated
mechanically without through any hydraulic means), so when there is
performed a negative work of bringing down the boom 28 at a
predetermined speed against its own weight, a potential energy of
the boom 28 can be converted to an electric energy by the boom
actuating electric motor 34, which electric energy can be recovered
in the battery 14. Thus, a highly efficient energy can be recovered
by allowing the boom actuating electric motor 34 to function as a
generator.
Likewise, since the rotatable superstructure 12 is rotated directly
by the rotating electric motor 22, when a negative work of braking
the rotation of the rotatable superstructure 12 is performed, the
rotation energy of the rotatable superstructure can be converted to
an electric energy by the rotating electric motor 22, which
electric energy can be recovered in the battery 14. Thus, the
recovery of a highly efficient energy can be effected by allowing
the rotating electric motor 22 to function as a generator. Further,
when the traveling of the hydraulic excavator is decelerated, the
recovery of energy can be done in the same way as above by allowing
the traveling electric motors 26L and 26R to function as
generators.
By these recoveries of energy it is possible to effectively
increase the continuous working time of the battery 14 while using
the battery as a power source. Besides, the boom actuating electric
motor 34, rotating electric motor 22 and traveling electric motors
26L, 26R are mounted on the working machine body side (the
rotatable superstructure 12 side in the drawings) and are
positioned near the center of gravity of the entire working
machine, so even if these electric motors 34, 22, 26L and 26R are
heavier than the hydraulic actuators, there is little fear that the
weight balance of the entire hydraulic excavator may become
unstable, nor is there any fear of an increase in inertia moment of
the boom 28. Besides, the mechanism for drive is simple. A mere
addition of a reduction mechanism suffices.
On the other hand, as arm actuating means and bucket actuating
means, which must be attached to the front end side of the boom 28,
there are used such hydraulic actuators of a relatively light
weight as the arm cylinder 38 and the bucket cylinder 40, so in
comparison with the case where electric motors are attached as such
arm actuating means and bucket actuating means to the boom 28, the
weight of the boom front end portion can be reduced to a great
extent and therefore it is possible to prevent the weight balance
from becoming unstable and also prevent an increase in inertia
moment of the boom.
Although in the above embodiment the arm 30 is connected to the
front end portion of the boom 28 and the bucket 32 is also
connected thereto through the arm 30, the present invention is also
applicable to the case where the bucket 32 is connected directly to
the boom 28 (that is, the arm 30 is not used) and the case where
the bucket 32 provided at the front end of the arm is not rotated
(that is, the bucket actuating means is not used). The present
invention is also applicable to a bucket wheel excavator wherein a
bucket wheel with plural buckets arranged on a circumference is
attached rotatably to the front end of a boom. In this case, a
hydraulic actuator (say, a hydraulic motor) may be used as means
for rotating the bucket wheel.
The traveling electric motors 26L and 26R may be omitted as the
case may be. For example, in a working machine using crawlers 54 as
traveling means, as shown in FIGS. 3a and 3b which illustrate the
second embodiment of the present invention, a frictional loss
caused by contact of the crawlers 54 with the ground surface is
large and so it is difficult to effect the regeneration of energy
in high efficiency. In this case, such hydraulic actuators as a
left-hand traveling hydraulic motor 52L and a right-hand traveling
hydraulic motor 2R may be used as traveling means, as shown in FIG.
4, to reduce the weight of the entire working machine.
In the present invention, as set forth above, either the operation
of the boom attached to the working machine body so as to be
capable of rising and falling or the rotation of the rotatable
superstructure carried rotatably on the lower carriage is performed
directly by using an electric motor, while the working portion
attached to the boom is actuated by means of a hydraulic actuator,
further, a hydraulic pump actuating electric motor is rotated with
the electric power supplied from the battery and the hydraulic oil
is fed to the above hydraulic actuator by means of a hydraulic pump
which is actuated by the said hydraulic pump actuating electric
motor. Therefore, it is possible to keep low the moment of inertia
of the boom, etc. and keep the weight balance of the entire working
machine in good condition; at the same time it is possible to
effect a highly efficient recovery of energy and thereby increase
the continuous working time of the battery.
* * * * *